The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Modern vehicles have been developed to increase energy efficiency and reduce noise and vibration during driving a vehicle. As one example, a stop-and-go system is incorporated in vehicles. A typical idle stop-and-go system is a system for improving fuel efficiency by preventing unnecessary fuel consumption caused by engine idling while a vehicle is not moving.
When a vehicle stops, the idle stop-and-go system automatically stops the engine several seconds later (i.e, cutting fuel to the engine), in a called idle stop mode. Subsequently, when a driver's intention to travel the vehicle is detected, for example, when a brake pedal is released or a gear shift occurs (e.g., gear shift to a drive stage), the system automatically restarts the engine without operation of an ignition key (referred to as an idle restart mode).
However, we have discovered that during the restart of the engine, a starter motor needs to generate a greater torque to restart the engine and to provide that the speed of the engine is high enough for an ignition process to be performed successfully, thereby dropping the energy efficiency, increasing vibration of the engine and time to restart engine.